In a Third Generation (3G) cellular system, such as the system 100 shown in FIG. 1, EU provides improvements to uplink (UL) data throughput and transmission latency. The system 100 includes a Node-B 102, a radio network controller (RNC) 104 and a wireless transmit/receive unit (WTRU) 106.
As shown in FIG. 2, the WTRU 106 includes a protocol architecture 200 which includes higher layers 202 and an EU medium access control (MAC), (MAC-e) 206, used to support EU operation between a dedicated channel MAC, (MAC-d) 204, and a physical layer (PHY) 208. The MAC-e 206 receives data for EU transmission from channels known as MAC-d flows. The MAC-e 206 is responsible for multiplexing data from MAC-d flows into MAC-e protocol data units (PDUs) for transmission, and for selecting proper EU transport format combinations (E-TFCs) for EU transmissions.
To allow for EU transmissions, physical resource grants are allocated to the WTRU 106 by the Node-B 102 and the RNC 104. WTRU UL data channels that require fast dynamic channel allocations are provided with fast “scheduled” grants provided by the Node-B 102, and channels that require continuous allocations are provided with “non-scheduled” grants by the RNC 104. The MAC-d flows provide data for UL transmission to the MAC-e 206. The MAC-d flows are either configured as scheduled or non-scheduled MAC-d flows.
An SG is the grant for scheduled data, (i.e., a “scheduled grant”). A “non-scheduled grant” is the grant for non-scheduled data. The SG is the power ratio that is converted to a corresponding amount of scheduled data that can be multiplexed, thus resulting in the scheduled data grant.
The RNC 104 configures non-scheduled grants for each MAC-d flow using radio resource control (RRC) procedures. Multiple non-scheduled MAC-d flows can be configured simultaneously in the WTRU 106. This configuration is typically performed upon radio access bearer (RAB) establishment, but may be reconfigured when necessary. The non-scheduled grant for each MAC-d flow specifies the number of bits that can be multiplexed into a MAC-e PDU. The WTRU 106 is then allowed to transmit non-scheduled transmissions up to the sum of non-scheduled grants, if multiplexed in the same transmission time interval (TTI).
Based on scheduling information sent in rate requests from the WTRU 106, the Node-B 102 dynamically generates scheduling grants for scheduled MAC-d flows. Signaling between the WTRU 106 and the Node-B 102 is performed by fast MAC layer signaling. The scheduling grant generated by the Node-B 102 specifies the maximum allowed EU dedicated physical data channel (E-DPDCH)/dedicated physical control channel (DPCCH) power ratio. The WTRU 106 uses this power ratio and other configured parameters to determine the maximum number of bits that can be multiplexed from all scheduled MAC-d flows into a MAC-e PDU.
Scheduled grants are “on top of” and mutually exclusive of non-scheduled grants. Scheduled MAC-d flows can not transmit data using a non-scheduled grant, and non-scheduled MAC-d flows can not transmit data using a scheduled grant.
The EU transport format combination set (E-TFCS) comprising all possible E-TFCs is known to the WTRU 106. For each EU transmission, an E-TFC is selected from a set of supported E-TFCs within the E-TFCS.
Since other UL channels take precedence over EU transmissions, the power available for EU data transmission on E-DPDCH is the remaining power after the power required for DPCCH, dedicated physical data channel (DPDCH), high speed dedicated physical control channel (HS-DPCCH) and EU dedicated physical control channel (E-DPCCH) is taken into account. Based on the remaining transmit power for EU transmission, blocked or supported states of E-TFCs within the E-TFCS are continuously determined by the WTRU 106.
Each E-TFC corresponds to a number of MAC layer data bits that can be transmitted in an EU TTI. Since there is only one MAC-e PDU per E-TFC that is transmitted in each EU TTI, the largest E-TFC that is supported by the remaining power defines the maximum amount of data, (i.e., the number of bits), that can be transmitted within a MAC-e PDU.
Multiple scheduled and/or non-scheduled MAC-d flows may be multiplexed within each MAC-e PDU based on absolute priority. The amount of data multiplexed from each MAC-d flow is the minimum of the current scheduled or non-scheduled grant, the available MAC-e PDU payload from the largest supported TFC, and the data available for transmission on the MAC-d flow.
Within the supported E-TFCs, the WTRU 106 selects the smallest E-TFC that maximizes the transmission of data according to the scheduled and non-scheduled grants. When scheduled and non-scheduled grants are fully utilized, available MAC-e PDU payload is fully utilized, or the WTRU 106 has no more data available and allowed to be transmitted, MAC-e PDUs are padded to match the next largest E-TFC size. This multiplexed MAC-e PDU and corresponding TFC are passed to the physical layer for transmission.
The SGs and non-SGs specify the maximum amount of data that can be multiplexed from specific MAC-d flows into MAC-e PDUs each EU TTI. Since the scheduled grants are based on the E-DPDCH/DPCCH ratio, the number of data bits allowed to be multiplexed per MAC-e PDU can not be explicitly controlled only to allow certain sizes which match the limited number of data sizes of the supported E-TFCs within the E-TFCS.
The remaining transmit power for EU data transmission determines the list of supported E-TFCs within the E-TFCS. Since the supported E-TFCs are determined from a limited number of E-TFCs in the TFCS, the granularity of allowed MAC-e PDU sizes will not allow for all possible MAC-d flow and MAC-e header combinations. Therefore, since the amount of MAC-d flow data allowed by the grants to be multiplexed into a MAC-e PDU will frequently not match the size of one of the supported E-TFCs, padding will be applied to the MAC-e PDU to match the smallest possible E-TFC size within the list of supported E-TFCs.
It is expected that when EU cells are operating at maximum capacity, the MAC-e PDU multiplexing is frequently limited by the SGs and non-SGs, and not limited by the largest supported E-TFC or the WTRU EU data available for transmission. In this case, depending on the granularity of specified E-TFCs within the E-TFCS padding required to match the selected E-TFC may exceed the multiplexing block size of MAC-d flow data including associated MAC-e header information. In this case, the effective data rate is unnecessarily reduced from what is allowed by the selected E-TFC and the physical resources required for its transmission.
FIG. 3 illustrates a MAC-e PDU 300. A MAC-e PDU header 302 and MAC-d flow data 304 allowed by scheduling and non-scheduling grants are multiplexed. Among a set of supported E-TFCs, the WTRU 106 selects the smallest E-TFC from a list of supported E-TFCs that is larger than MAC-e PDU header 302 and MAC-d flow data 304. Padding 306 is then applied to the MAC-e PDU to match the selected E-TFC size. However, the padding 306 may exceed the multiplexing block size of MAC-d flow data. In this case, physical resources used in the EU transmission are under utilized and the effective WTRU data rate is unnecessarily reduced.
MAC-e PDU multiplexing logic provides more efficient data multiplexing and improved radio resource utilization for the cases where MAC-e PDU multiplexing is limited by scheduled and/or non-scheduled grants, and not limited by the largest supported E-TFC or available EU data for transmission. The amount of data allowed to be multiplexed from MAC-d flows into MAC-e PDUs according to the scheduled and non-scheduled grants is either increased or decreased to more closely match the next smaller or next larger E-TFC size relative to the amount of data allowed to be multiplexed by the scheduled and non-scheduled grants.
FIG. 4 is a flow diagram of a process 400 for generating MAC-e PDUs. In step 405, a WTRU receives a scheduled data grant from a Node-B and/or non-scheduled grants from an RNC. In step 410, an E-TFC transport block size is selected based on the amount of data allowed to be multiplexed according to the scheduled and non-scheduled grants. In step 415, the maximum amount of scheduled and/or non-scheduled data allowed to be transmitted according to the scheduled and non-scheduled grants is quantized so that the amount of data multiplexed into each MAC-e PDU more closely matches the selected E-TFC transport block size.
FIG. 5 is a flow diagram of a process 500 for generating MAC-e PDUs. In step 505, a WTRU receives a scheduled data grant from a Node-B and/or non-scheduled grants from an RNC. In step 510, an E-TFC transport block size is selected based on the amount of data allowed to be multiplexed according to the scheduled and non-scheduled grants. In step 515, the amount of buffered WTRU data allowed to be multiplexed by the at least one grant is quantized so that the sum of scheduled and non-scheduled data (including MAC header and control information) multiplexed into each EU MAC-e PDU more closely matches the selected E-TFC transport block size.
Alternatively, granularity of E-TFC sizes is defined within the E-TFCS so that the difference between E-TFC sizes is not greater than one MAC-d PDU and the associated MAC-e header overhead. E-TFCs are defined for each possible MAC-d flow multiplexing combination and associated MAC-e header overhead. By optimizing the E-TFCS in this way, the padding required after MAC-d flow data is multiplexed according to the scheduled and non-scheduled grants will not exceed the size of possible MAC-d flow multiplexing block sizes.
FIG. 6 is a flow diagram of a process 600 for generating a MAC-e PDU. A largest E-TFC is selected from a set of supported E-TFCs that is smaller than the size of MAC-d flow data and MAC-e control signaling allowed by current grants 602. As a result, the selected E-TFC permits a decreased amount of data to be multiplexed onto the MAC-e PDU relative to the amount allowed by the grants, to more closely match the largest E-TFC size that is smaller than the amount required by scheduled and non-scheduled grants. The MAC-d flow data (scheduled and/or non scheduled) is multiplexed into a MAC-e PDU in accordance with an absolute priority until no more MAC-d flow data blocks can be added within the limit of the selected E-TFC 604. The MAC-e PDU is padded to match the selected E-TFC size 606.
FIG. 7 shows conventional uplink spreading and gain factor usage for high speed uplink power access (HSUPA). The power of the E-DPCCH and the E-DPDCH(s) is set relative to the DPCCH, such that gain factors are used for scaling the uplink channels relative to each other. As shown in FIG. 7, the gain factors are applied individually for E-DPCCH and each E-DPDCH. βec is the gain factor for the E-DPCCH and βed,k is the gain factor for the E-DPDCH(s). The WTRU derives these gain factors from higher layer signaling.
The E-DPCCH is scaled with the gain factor βec, which is given by:βec=βc·Aec;  Equation (1)where βc is the gain factor of the DPCCH. βc is either signaled by higher layers to the WTRU, or is computed. The ratio Aec is derived from the parameter ΔE-DPCCH signaled by higher layers, (e.g., at call setup). Table 1 shows the meaning of the signaled values for ΔE-DPCCH. The WTRU will scale the E-DPCCH in relation to the DPCCH according to the quantized amplitude ratio.
TABLE 1Signaled values forQuantized amplitude ratiosΔE-DPCCHAec = βec/βc830/15724/15619/15515/15412/153 9/152 8/151 6/150 5/15
During compressed frames, the E-DPCCH gain factor βec needs to be scaled. This is performed in order to avoid that the E-DPCCH power is increased by the offset that is applied to the DPCCH during compressed frames. The uplink DPCCH slot formats that have TFCI bits contain fewer pilot bits than the formats for normal (non-compressed) mode. The reason for this is that the number of TFCI bits is always the same during a frame to ensure robust transport format detection. Therefore, in order to keep the same channel quality, the energy of the pilot must be kept equal, and the power of the DPCCH is therefore increased by the following factor: Npilot, N/Npilot, C.
Therefore, if a 2 ms TTI overlaps with a compressed frame:
                                          β            ec                    =                                    β                              c                ,                C                ,                j                                      ·                          A              ec                        ·                                                            N                                      pilot                    ,                    C                                                                    N                                      pilot                    ,                    N                                                                                      ;                            Equation        ⁢                                  ⁢                  (          2          )                    where βc,C,j is a beta factor for DPCCH in compressed frames for the jth transport format combination (TFC) such that βc,C,j=1 when no DPDCH is configured, Npilot,c is the number of pilot bits per slot on DPCCH in compressed frames, and Npilot,N is the number of pilot bits per slot in non-compressed frames.
If a 10 ms TTI overlaps with a compressed frame, the E-DPCCH gain factor βec is additionally scaled (increased) to take into account that less slots are available for transmission during this frame. In order to get a good transmission quality, the transmitted energy per information bit is the same, independent of whether compressed mode is used in a frame or not. Therefore, βec is additionally scaled with the factor 15/Nslots, C:
                                          β            ec                    =                                    β                              c                ,                C                ,                j                                      ·                          A              ec                        ·                                                            15                  ·                                      N                                          pilot                      ,                      C                                                                                                            N                                          slots                      ,                      C                                                        ·                                      N                                          pilot                      ,                      N                                                                                                          ;                            Equation        ⁢                                  ⁢                  (          3          )                    where Nslots,C is the number of non-discontinuous transmission (non-DTX) slots in this compressed frame.
As shown in FIG. 7, there can be one or more E-DPDCH(s), and each of them is scaled with its own gain factor. The gain factors may vary on radio frame basis or sub-frame basis depending on whether the E-DCH TTI is 10 ms or 2 ms, respectively. The gain factor βed,k for the kth E-DPCCH is determined by the transport format combination on E-DCH (E-TFC) carried in this TTI, and depending on the hybrid automatic repeat request (HARQ) profile for the data carried in this TTI. The E-TFC describes the size of the transport block carried in a TTI. This parameter therefore influences the required transmission power.
For each data flow (MAC-d flow), higher layers can configure an individual HARQ profile. The HARQ profile includes the power offset and maximum number of HARQ retransmissions to use for this MAC-d flow. This can be used to fine-tune operating points for different data flows. The WTRU determines the gain factor βed,k based on parameters signaled by higher layers, (e.g., at call setup).
First, a “reference E-TFC” needs to be determined in the WTRU for the E-TFC carried in the regarded TTI. A list of reference E-TFCs containing up to 8 reference E-TFCs is signaled by higher layers. The reference E-TFC is selected as close as possible to the regarded E-TFC. Then, a reference gain factor βed,ref is determined for the selected reference E-TFC as follows:βed,ref=βc·Aed,ref;  Equation (4)where βc is the gain factor of the DPCCH. The ratio Aed,ref is derived from the parameter ΔE-DPDCH signaled by higher layers for the selected reference E-TFC. Table 2 shows the meaning of the signaled values for ΔE-DPDCH. The reference E-TFC concept is used in order to avoid the signaling overhead which would result from signaling a ΔE-DPDCH value for all possible E-TFC values.
TABLE 2Signaled values forQuantized amplitude ratiosΔE-DPDCHAed, ref = βed/βc29168/15 28150/15 27134/15 26119/15 25106/15 2495/152384/152275/152167/152060/151953/151847/151742/151638/151534/151430/151327/151224/151121/151019/15917/15815/15713/15612/15511/154 9/153 8/152 7/151 6/150 5/15
However, this reference gain factor cannot directly be used for scaling the E-DPDCHs, since the reference E-TFC does not reflect the actual E-TFC in terms of number of data bits contained and number of E-DPDCHs required for transmission. Furthermore, the HARQ profile needs to be considered.
Therefore, for the E-TFC to be transmitted in the TTI under consideration (the jth E-TFC), a temporary variable βed,j,harq is computed as follows:
                                          β                          ed              ,              j              ,              harq                                =                                    β                              ed                ,                ref                                      ⁢                                                            L                                      e                    ,                    ref                                                                    L                                      e                    ,                    j                                                                        ⁢                                                                                K                                          e                      ,                      j                                                                            K                                          e                      ,                      ref                                                                                  ·                              10                                  Δ                  ⁢                                                                          ⁢                                      harq                    /                    20                                                                                      ;                            Equation        ⁢                                  ⁢                  (          5          )                    where Le,ref is the number of E-DPDCHs used for the reference E-TFC, Le,j is the number of E-DPDCHs used for the jth E-TFC, Ke,ref is the number of data bits of the reference E-TFC, Ke,j is the number of data bits of the jth E-TFC, and Δharq is the HARQ offset for the specific data flow to be transmitted (so called “MAC-d flow”) as signaled by higher layers (see Table 3).
TABLE 3Signaling values forPower offset valuesΔharqΔharq [dB]66554433221100Le,ref and Le,j represent “equivalent” number of physical channels. Normally they are equal to number of used E-DPDCHs except for two cases:                1) 2×SF2 case: Le,ref and Le,j should be 4 instead of 2; and        2) 2×SF2+2×SF4 case: Le,ref and Le,J should be 6 instead of 4.Therefore, the calculated βed,j,harq must be scaled by a factor of √{square root over (2)} for SF=2 codes. The unquantized gain factor βed,k,j,uq is set to √{square root over (2)}×Δed,j,harq for E-DPDCHs using spreading factor 2 and equal to βed,j,harq otherwise. The ratio βed,k,j,uq/βC is now quantized according to Table 4 to obtain the ratio βed,k,/βC.        
TABLE 4Quantized amplitude ratiosβed, k,/βc168/15 150/15 134/15 119/15 106/15 95/1584/1575/1567/1560/1553/1547/1542/1538/1534/1530/1527/1524/1521/1519/1517/1515/1513/1512/1511/15 9/15 8/15 7/15 6/15 5/15
During compressed frames, the E-DPDCH gain factor βed,k needs to be scaled as follows. The factors applied for the scaling the E-DPDCH have been introduced already in the E-DPCCH section above.
For 2 ms TTI, the gain factor used for the jth E-TFC in a compressed frame is given by:
                                          β                          ed              ,              C              ,              j                                =                                    β                              c                ,                C                ,                j                                      ·                          A              ed                        ·                                                            L                                      e                    ,                    ref                                                                    L                                      e                    ,                    j                                                                        ·                                                            K                                      e                    ,                    j                                                                    K                                      e                    ,                    ref                                                                        ·                          10                              Δ                ⁢                                                                  ⁢                                  harq                  /                  20                                                      ·                                                            N                                      pilot                    ,                    C                                                                    N                                      Pilot                    ,                    N                                                                                      ;                            Equation        ⁢                                  ⁢                  (          6          )                    where βc,C,j is the DPCCH beta factor in compressed frames for jth TFC (βc,C,j=1 when no DPDCH is configured), Npilot,C is the number of pilot bits per slot on DPCCH in compressed frames, Npilot,N is the number of pilot bits per slot in non-compressed frames, and Nslots,C is the number of DTX slots in this compressed frame.
For 10 ms TTI, the gain factor used for the jth E-TFC in a compressed frame is given by:
                                          β                          ed              ,              C              ,              j                                =                                    β                              c                ,                C                ,                j                                      ·                          A              ed                        ·                                                            L                                      e                    ,                    ref                                                                    L                                      e                    ,                    j                                                                        ·                                                            K                                      e                    ,                    j                                                                    K                                      e                    ,                    ref                                                                        ·                          10                              Δ                ⁢                                                                  ⁢                                  harq                  /                  20                                                      ·                                                            15                  ·                                      N                                          pilot                      ,                      C                                                                                                            N                                          slots                      ,                      I                                                        ·                                      N                                          pilot                      ,                      N                                                                                                          ;                            Equation        ⁢                                  ⁢                  (          7          )                    where βc,C,j is the beta factor in compressed frames for the jth TFC (=1 when no DPDCH is configured), Npilot,C is the number of pilot bits per slot on DPCCH in compressed frames, Npilot,N is the number of pilot bits per slot in non-compressed frames, and Nslots,I is the number of non-DTX slots in the first frame used for transmitting the data.
Note that in the 10 ms case, retransmissions on E-DPDCH also require scaling when the corresponding initial transmission overlapped a compressed frame (but the frame with the retransmission does not). When the E-DCH TTI is 10 ms and the current frame is not compressed, but is a retransmission for which the corresponding first transmission was compressed, βed,R,j represents the gain factor that shall be applied to the jth E-TFC as follows:
                                          β                          ed              ,              R              ,              j                                =                                    β                              ed                ,                j                                      ·                                          15                                  N                                      slots                    ,                    I                                                                                      ;                            Equation        ⁢                                  ⁢                  (          8          )                    where βed,j is the gain factor used for the jth E-TFC in non-compressed frames.
The prior art describes the principles by which an E-TFC selection procedure should follow, but fails to describe a specific method and apparatus for determining the actual SGP. Thus, although the prior art requires the computation of an SGP, a particular method or apparatus for performing such a computation is not described. Although more than one approach for computing SGP may exist, a method and apparatus for computing an optimum, (i.e., “maximum” or “highest priority”), SGP is desired.